I honestly think that, in that position, I might go for the SVS. The benefit of the axiom sub is that it has its own EQ and correction so it can help you achieve good, flat in-room response. The SVS might require more playing with placement and other level settings (although both will require these steps). However, if you compare the output of the two subs anechoically, the SVS bests the Axiom by about 13dB at 20Hz. Of course, the SVS has 400w of power and another 12" cone.
The SVS is much bigger than the Axiom too. I guess it really depends on how much space you can afford to use.
SVS: Size: 18" wide, 25" tall and 28" deep. Weight: 140 pounds
Axiom: Dimens. (HxWxD)(in.) 19.5 x 15 x 19.5
Weight 70 lbs
How much sub do you want?